RFR: 8266874: Clean up C1 canonicalizer for TableSwitch/LookupSwitch

[Yi Yang]

Clean up C1 canonicalizer for TableSwitch/LookupSwitch

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Commit messages:
 - canonicalizer cleanup

Changes: https://git.openjdk.java.net/jdk/pull/3966/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3966&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266874
  Stats: 34 lines in 1 file changed: 0 ins; 34 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3966.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3966/head:pull/3966

PR: https://git.openjdk.java.net/jdk/pull/3966